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1.
The effect of low carboxyl-functionalized multi-walled carbon nanotubes (f-MWCNTs) loading on the crystallization behavior of biodegradable poly(butylene adipate) (PBA) was studied with various techniques in this work. For the nonisothermal melt crystallization, f-MWCNTs accelerate the crystallization process of PBA apparently due to the heterogeneous nucleation effect. The Ozawa method fails to describe the nonisothermal crystallization process of neat PBA and its nanocomposite. Isothermal melt crystallization kinetics of neat PBA and its nanocomposite was analyzed by the Avrami equation. The overall isothermal crystallization rate of neat PBA and its nanocomposite increases with increasing crystallization temperature. The addition of f-MWCNTs accelerates the isothermal crystallization of PBA as compared with that of neat PBA at a given crystallization temperature, indicative of the nucleating agent effect of f-MWCNTs; however, the crystallization mechanism does not change. The crystal structure of PBA remains unchanged in the PBA/f-MWCNTs nanocomposite despite the presence of f-MWCNTs. 相似文献
2.
M. Evstatiev S. Simeonova K. Friedrich X.-Q. Pei P. Formanek 《Journal of Materials Science》2013,48(18):6312-6330
Both polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) are biodegradable polymers. They are thermoplastics which can be processed using conventional polymer processing methods. In this study, microfibrillar-reinforced composites (MFC) based on PLA/PBAT (PLA/Ecoflex®) blends in different weight ratios were prepared under industry-relevant conditions by melt extrusion followed by continuous cold drawing of the extrudates. Strip-like specimens (films) and plates (laminates) of the drawn blends were prepared by compression molding (CM) at processing temperature above the melting temperature (T m) of PBAT, but below T m of PLA. SEM and WAXS observations show that the extruded blend components are isotropic, but become highly oriented after drawing, and they are converted into MFC-structured polymer–polymer composites after CM. An effect of PLA microfibrils on the non-isothermal crystallization of the Ecoflex during cooling from the melt, associated with the formation of crystalline regions of the matrix around the fibrils, was observed. Depending on the blend composition, the compression-molded samples possess a 3- to 7-time higher tensile strength as well as a 15–30 higher modulus than the neat Ecoflex. In addition, the MFC-structured plates exhibited superior barrier properties compared to the neat Ecoflex, e.g., the oxygen permeability decreased by up to 5 times. 相似文献
3.
Discontinuity in crystallization rates and a new and unusual morphology consisting of thickened straight-stalks crystal lamellae with also straight branches radiating out from a common nucleus were observed in blends of poly(vinyl acetate) (PVAc) with poly(1,4-butylene adipate) (PBA). The discontinuity in the crystal growth and mechanisms of straight-dendrite morphology of the PVAc/PBA blends were analyzed using polarized-light optical microscopy (POM), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD). The discontinuity in crystallization rate and dendritic morphology occurred only at or near PVAc/PBA 10/90 blend composition upon crystallization at high-temperature regimes of Tc = 30-33 °C. By comparison, when crystallized at the same temperatures, PVAc/PBA blends of amorphous polymer loading greater than 15% or the neat PBA (amorphous polymer loading = 0) developed no dendrites but only typical Maltese-cross spherulites. Mechanism of straight dendrites in the blends is preliminarily expounded. Detailed interpretation requires further analyses. 相似文献
4.
生物质基降解塑料PBS的研制 总被引:1,自引:0,他引:1
以玉米和小麦秸秆为原料,通过粉碎、闪蒸等化学和物理处理和加工,并进行初步糖化,使其可作为微生物可发酵的糖源。以新的琥珀酸产生菌株-产琥珀酸放线杆菌及重组微生物作为发酵的微生物菌株对生物质基糖源进行厌氧发酵,在液体深层厌氧培养条件下制备琥珀酸。通过正交实验研究了发酵液中葡萄糖、酵母膏、磷酸盐、尿素、K+、Mg2+、Mn2+等因素对琥珀色产量的影响。通过离子色谱柱脱色,分离得到纯度为95%以上琥珀酸,秸秆转化率达到75%。利用生物法制备的琥珀酸在Sn-Ti系纳米催化剂作用下通过一步法合成了重均分子量超过20万降解塑料聚(琥珀酸丁二醇酯)。 相似文献
5.
6.
The morphologies of melt blends of poly(butylene terephthalate) (PBT) and bisphenol A polycarbonate (PC) toughened with a core/shell impact modifier have been characterized by transmission and scanning electron microscopy. Selective staining with ruthenium and osmium tetroxide and etching with diethylene triamine have been used to assess the distribution of the various blend components and investigate the effects of thermal history on morphology. Strong evidence for partial melt miscibility of PC and PBT and rate-dependent segregation during cooling is presented. 相似文献
7.
Melt blends of poly (butylene terephthalate) (PBT) and poly (ethylene naphthalate) (PEN) with 30, 40, 50, 60 and 70 wt% PEN
were prepared using a single screw extruder and injection moulding machine. 13C and 1H nuclear magnetic resonance (NMR) spectra were obtained with a Bruker DRX-400 instrument, on solutions prepared by dissolving
samples of the homopolymers and each blend in deuterated trifluoroacetic acid + chloroform mixtures (1:1 by volume). The absence
of new signals in 1H and 13C spectra, that would be expected to result from transesterification reactions in the PBT + PEN blend system, provides convincing
evidence that such reactions do not occur in these blends under the melt processing conditions that were used. In the light
of published work on solid-state NMR studies of these and related blend systems, and our observations of partial miscibility
with a very small domain size, together with substantial enhancement of the mechanical properties of PBT by blending with
PEN, we conclude that the improvement in mechanical properties arises from molecular scale mixing of the homopolymers and
strong but non-covalent bonding interactions over the very large interfacial area between the PBT-rich and PEN-rich phases. 相似文献
8.
Dylan Dae Bong Jung Debes Bhattacharyya Allan J. Easteal 《Journal of Materials Science》2005,40(18):4775-4783
Melt blends of poly(butylene terephalate) (PBT) and poly(ethylene naphthalate) (PEN) with 30 and 60 wt% PEN were prepared
using a single screw extruder and an injection moulding machine. Stress relaxation tests for the specimens of PBT/PEN blends
and the homopolymers were carried out using an Instron testing machine in an Instron environmental chamber. The Taguchi method
of experimental design analysed how different levels of temperature, PEN content and initial stress affected the relaxation
behaviour of PBT/PEN blends and homopolymers. From the response tables and analyses of main and interaction effects, it was
shown that the most significant factor was temperature, followed by PEN content and then the initial stress. Consequently,
high temperature, low PEN content and high initial stress speeded up stress relaxation rate of specimens. Interaction effects
between factors were insignificant.
To fit the relaxation curves of the PBT/PEN blends and the homopolymers at different temperatures, PEN contents and the initial
stresses, four different equations were attempted with Matlab™, which determined the coefficients of these functions using
the experimental data of stress change with time. The simulated curves from the most suitable function among them were shown
using the calculated coefficients to predict the relaxation behaviour of PBT/PEN blends (50% PEN) at temperatures of 30 and
60°C with an initial stress of 7 MPa. 相似文献
9.
Srikanth Pilla Seong G. Kim George K. Auer Shaoqin Gong Chul B. Park 《Materials science & engineering. C, Materials for biological applications》2010,30(2):255-262
Foamed poly(lactide) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends were processed via the microcellular extrusion process using CO2 as a blowing agent. Talc has been added to promote heterogeneous nucleation. Two types of PLA/PBAT blend systems were investigated: Ecovio, which is a commercially available compatibilized PLA/PBAT blend; and a non-compatibilized PLA/PBAT blend at the same PLA/PBAT ratio (i.e., 45:55 by weight percent). Six different formulations were investigated: pure PLA, PLA-talc, Ecovio, Ecovio-talc, non-compatibilized PLA/PBAT blend, and non-compatibilized PLA/PBAT-talc. The effects of various processing parameters such as die temperature, talc and compatibilization on various foaming properties such as cell morphology, volume expansion ratio (VER), open cell content (OCC) and crystallinity were investigated. As per the DSC thermograms, it was observed that compatibilization has merged the two distinctive melting peaks of PLA and PBAT into a single peak while lowering the peak temperature. In general, the addition of talc has decreased the average cell size and VER and increased the cell density and crystallinity; however, it has varying effects on the open cell content. Compatibilization has reduced the average cell size and volume expansion but increased the cell density and had varying and no effects on the OCC and crystallinity, respectively. Similar to compatibilization, the die temperature was found to have varying and no effects on the OCC and crystallinity, respectively. Except for PLA and non-compatibilized PLA/PBAT blend, the cell size and VER of all other formulations did not vary much throughout the entire temperature range (130–150 °C). The cell density was found to be insensitive to die temperatures except for Ecovio and Ecovio-talc. 相似文献
10.
Sangcheol Kim Won Ho Jo Junkyung Kim Soon Ho Lim Chul Rim Choe 《Journal of Materials Science》1999,34(1):161-168
In an effort to investigate the effect of the crystalline morphology of a poly(butylene terephthalate) (PBT) phase on the toughening of PBT/epoxy blends, the blends, having different degrees of perfectness of the PBT crystalline phase, were prepared by blending PBT and epoxy at various temperatures ranging from 200 to 240 °C. As the blending temperature decreases, the degree of perfectness of the PBT crystalline phase increases as a result of the increase of crystal growth rate. For PBT/epoxy blends, the change in crystalline morphology induced by processing may be the most important cause for the dependency of the fracture energy on blending temperatures. It has been found that PBT phases with a well-developed Maltese cross are most effective for epoxy toughening. This dependency reveals the occurrence of a phase transformation toughening mechanism. Also, the higher relative enhancement of fracture energy of a higher molecular weight epoxy system is further indirect evidence for a phase transformation toughening mechanism. Some other toughening mechanisms observed from the fracture surfaces, such as crack bifurcation, crack bridging, and ductile fracture of PBT phases, have been found to also be affected by the blending temperatures. 相似文献
11.
Ray SS Vaudreuil S Maazouz A Bousmina M 《Journal of nanoscience and nanotechnology》2006,6(7):2191-2195
This communication describes the preparation, characterization and properties of biodegradable poly(butylene succinate) (PBS)/multi-walled carbon nanotubes (MWCNTs) nanocomposite. Nanocomposite was prepared by melt-blending in a batch mixer and the amount of MWCNTs loading was 3 wt%. State of dispersion-distribution of the MWCNTs in the PBS matrix was examined by scanning and transmission electron microscopic observations that revealed homogeneous distribution of stacked MWCNTs in PBS matrix. The investigation of the thermomechanical behavior was performed by dynamic mechanical thermal analysis. Results demonstrated substantial enhancement in the mechanical properties of PBS, for example, at room temperature, storage flexural modulus increased from 0.64 GPa for pure PBS to 1.2 GPa for the nanocomposite, an increase of about 88% in the value of the elastic modulus. The tensile modulus and thermal stability of PBS were moderately improved after nanocomposite preparation with 3 wt% of MWCNTs, while electrical conductivity of neat PBS dramatically increased after nanocomposite formation. For example, the in plane conductivity increased from 5.8 x 10(-9) S/cm for neat PBS to 4.4 x 10(-3) for nanocomposite, an increase of 10(6) fold in value of the electrical conductivity. 相似文献
12.
Seung Hee Ha Jong-Ho Hwang Do Hyung Kim Min-Dae Kim Cheol-Woong Choi Young-Il Jeong Chung Wook Chung Cy Hyun Kim Dae Hwan Kang 《Materials Research Bulletin》2012,47(10):2735-2738
The aim of this study was to prepare sunitinib-loaded biodegradable films using poly(l-lactide-co-?-caprolactone) (PLCL) for anti-tumor drug delivery. Sunitinib-loaded PLCL film has a rough surface, while empty film has a smooth surface. PLCL film loaded with 5% (w/w) sunitinib showed an absence of a crystalline peak of sunitinib, while sharp peaks were observed at 10% (w/w) loading, indicating that sunitinib was molecularly distributed in the polymer matrix at 5% (w/w). A drug release study revealed an initial burst during the first 2 h, followed by continuous release until 24 h. Since weight loss of film was <10% for 1 week, drug release mechanism was dominantly dependent on the diffusion-mediated release of drugs to the medium. Sunitinib has a dose-dependent anti-proliferation effect against HuCC-T1 human cholangiocarcinoma cells in vitro. These results indicate that sunitinib-loaded PLCL film is a appropriate candidate as a vehicle for anti-tumor drug delivery. 相似文献
13.
《材料与设计》2015
Core-shell structured polyacrylic nanoparticles (named CSPN) impact modifiers consisting of a rubbery poly(n-butyl acrylate) core and a rigid poly(methyl methacrylate) shell with a size of about 352 nm were synthesized by seed emulsion polymerization. The CSPN modifier with core-shell weight ratio 80/20 was used to toughen poly(butylene terephthalate) (PBT) by melt blending. With an increase in CSPN content, the impact strength and the elongation at break of PBT/CSPN blends increased significantly compared with those of PBT; however, the tensile strength decreased. It was found that the polymerization had a very high instantaneous conversion (> 93%) and overall conversion (99%). The core-shell structure of CSPN was examined by means of transmission electron microscope. Scanning electron microscope was used to observe the morphology of CSPN particle and fractured surfaces of the blends. The dynamic mechanical analyses of PBT/CSPN blends showed two merged transition peaks of PBT matrix, with the presence of CSPN modifier, which was responsible for the improvement of PBT toughness. The results indicated that the notched impact strength of PBT/CSPN blend with a weight ratio of 80/20 was 8.61 times greater than that of pure PBT where the brittle-ductile transition point appeared. 相似文献
14.
Poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) were melt-blended in the presence of glycidyl methacrylate
(GMA) by twin-screw extrusion. The physical properties, phase morphology, thermal properties, and melt rheological behavior
of the blends were investigated by tensile tests, Charpy impact tests, scanning electron microscopy (SEM), differential scanning
calorimetry (DSC), and advanced rheology expended system (ARES). With 2 or 5 wt% GMA, the tensile toughness of the PLA/PBAT
blend was greatly increased without severe loss in tensile strength. The impact strength of the blend was also significantly
improved at 1 wt% of GMA addition but ultimately trended to be saturated with increasing GMA. SEM micrographs revealed that
better miscibility and more shear yielding mechanism were involved in the toughening of the blend. DSC results indicated that
the blend is still a two-phase system in the presence of reaction agent and the addition of GMA was found to enhance the interfacial
adhesion between PLA and PBAT. Rheological results revealed that the addition of T-GMA increased the storage moduli (G′), loss moduli (G′′) and complex viscosity of the blends at nearly all frequencies. The decreased shear-thinning tendency of the blends in
the presence of T-GMA also implied improved melt stability during processing. 相似文献
15.
Jean-Luc Audic Laurent Legentil Caroline Nugier-Chauvin Vincent Ferrières Michel Potel Thierry Roisnel 《Journal of Materials Science》2012,47(15):5806-5814
A biodegradable material was prepared by blending sodium caseinate (NaCAS) with poly(butylene adipate-co-terephtalate) (PBAT). The best composition was selected from mechanical testing of PBAT/NaCAS blends for further manufacture of a partially biobased film able to deliver a bioactive compound. From stress–strain testing, it was determined that the best mechanical properties while keeping maximum NaCAS content were obtained for 80/20 w/w PBAT/NaCAS blends plasticized with 10 % Glycerol (Gly). The surfactant octyl-β-d-galactofuranoside was used as an antitubercular agent and directly incorporated in the blend during hot mixing. The biodegradable films containing 1–5 % by weight of galactofuranoside were observed by SEM and showed crystalline structures on their surface. From X-ray diffraction studies, it was demonstrated that on the surface, the octyl galactofuranoside crystallized orthorhombic with space group P212121. The molecular packing calculated from X-ray data showed bilayer structures with interdigitated octyl chains. Finally, the mycobacteriostatic properties of Gly-plasticized PBAT/NaCAS films were evaluated from a modified Kirby-Bauer test. 相似文献
16.
R.A. Carvalho T.M.C. Maria I.C.F. Moraes P.V.A. Bergo E.S. Kamimura A.M.Q.B. Habitante P.J.A. Sobral 《Materials science & engineering. C, Materials for biological applications》2009,29(2):485-491
The aim of this work was to study the effect of the hydrolysis degree (HD) and the concentration (CPVA) of two types of poly(vinyl alcohol) (PVA) and of the type (glycerol and sorbitol) and the concentration (CP) of plasticizers on some physical properties of biodegradable films based on blends of gelatin and PVA using a response-surface methodology. The films were prepared with a film forming solutions (FFS) with 2 g of macromolecules (gelatin+PVA)/100 g de FFS. The responses analyzed were the mechanical properties, the solubility, the moisture content, the color difference and the opacity. The linear model was statistically significant and predictive for puncture force and deformation, elongation at break, solubility in water, moisture content and opacity. The CPVA affected strongly the elongation at break of the films. The interaction of the HD and the CP affected this property. Moreover, the puncture force was affected slightly by the CPVA. Concerning the solubility in water, the reduction of the HD increased it and this effect was greater for high CPVA values. In general, the most important effect observed in the physical properties of the films was that of the plasticizer type and concentration. The PVA hydrolysis degree and concentration have an important effect only for the elongation at break, puncture deformation and solubility in water. 相似文献
17.
Dylan Dae Bong Jung D. Bhattacharyya A. J. Easteal 《Journal of Materials Science》2003,38(12):2597-2606
The tensile modulus, tensile strength and impact strength of melt blends of (a) poly(ethylene naphthalate) (PEN) and poly(butylene terephalate) (PBT) with 30, 40, 50, 60 and 70 wt% PEN, (b) Nylon66 and PEN with 30, 50 and 70 wt% Nylon66 were measured, and thermal/thermomechanical properties were analysed by differential scanning calorimetry and dynamic mechanical thermal analysis. Scanning electron microscopy was used for examination of the fracture surfaces of the blends.All PBT/PEN blends show two glass transitions corresponding to the presence of two phases: the glass transition temperature, T
g, of the phase with the lower T
g increases with increasing PEN content, and T
g for the phase with higher T
g decreases with increasing PBT content. The implication is that the two polymers are partially miscible, and scanning electron microscopy of fracture surfaces reveals a very small (sub-micron) domain size. Nylon66/PEN blends also show two phases, but the domain size is of the order of m and there is no evidence of partial miscibility.Up to 50 weight proportions PBT does not lower the tensile strength of PBT/PEN blends, and the tensile strength lies between values predicted by the rule of mixtures and a modified rule of mixtures. Incorporation of at least 40% PEN in PBT increases impact strength, but blending with smaller proportions of PEN decreases impact strength. By contrast, blending of Ny66 and PEN results in reduction of tensile strength for all blend compositions. 相似文献
18.
Bandyopadhyay J Maity A Khatua BB Ray SS 《Journal of nanoscience and nanotechnology》2010,10(7):4184-4195
The thermal and rheological properties of clay-containing poly[(butylene succinate)-co-adipate] (PBSA) nanocomposites are reported. The nanocomposites of PBSA with various weight percentages of organically modified montmorillonite (OMMT) loadings have been prepared by melt-mixing in a batch-mixer. The melting and crystallization behaviours of PBSA and its nanocomposites have been studied using differential scanning calorimeter (DSC). The melt-state rheological properties of pure PBSA and its nanocomposites containing different amounts of OMMT have been studied in detail. The reason for this is that the rheological responses of any nanofilled polymeric materials are strongly related by their dispersed structure and the interfacial characteristic. Results show that the structural strength of all samples remains constant in the examined time interval at an experimental temperature. The dominant viscous behaviour of pure PBSA is getting suppressed up to a certain OMMT loading (4 wt%). Nanocomposite containing 5 wt% OMMT is showing almost "at the gel point" behaviour, suggesting that the material is behaving near the borderline between liquid and solid; while nanocomposite containing 6 wt% OMMT is showing the gel character. The dispersed structure of the clay particles in the PBSA matrix was studied by scanning transmission electron microscopy (STEM). Results show that the stacked and intercalated silicate layers are nicely dispersed in the case of all nanocomposites. However, with a systematic increase in OMMT loading, the dispersed clay structure of the nanocomposites changes from a highly delaminated to a flocculated and then to a stacked-intercalated structure. In the case of all nanocomposites, melt-state rheological properties are in good agreement with the STEM observations. 相似文献
19.